Ultrasound catheter devices and methods

ABSTRACT

Ultrasound catheter devices and methods provide enhanced disruption of blood vessel obstructions. Generally, an ultrasound catheter device includes an elongate flexible catheter body with one or more lumens, an ultrasound transmission member extending longitudinally through the catheter body lumen and a distal head coupled with the transmission member and positioned adjacent the distal end of the catheter body for disrupting occlusions. A proximal housing of the catheter device may include one or more features for dissipating heat from the ultrasound transmission wire, such as a fluid inlet aperture for passage of fluid, use of heat conductive materials in the proximal housing, surface features to increase the housing&#39;s surface area, heat conductive members disposed adjacent the transmission member and the like. Various irrigation fluids may be used, such as cooled, oxygen supersaturated or lubricious fluids.

This application is related to the following U.S. patent applicationSer. Nos.: 10/229,371, filed Aug. 26, 2002, entitled “UltrasoundCatheter for Disrupting Blood Vessel Obstructions” (Attorney Docket No.021577-000400US); 10/345,078, filed Jan. 14, 2003, entitled “UltrasoundCatheter and Methods for Making and Using Same” (Attorney Docket No.021577-000600US); 10/375,903, filed Feb. 26, 2003, entitled “UltrasoundCatheter Apparatus” (Attorney Docket No. 021577-000700US); 10/410,617,filed Apr. 8, 2003, entitled “Improved Ultrasound Catheter Devices andMethods” (Attorney Docket No. 021577-000800US); and 10/722,209, filedNov. 24, 2003, entitled “Steerable Ultrasound Catheter” (Attorney DocketNo. 021577-000900US). The full disclosures of all of the above-listedpatent applications are all hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices and methods.More specifically, the present invention relates to ultrasound catheterdevices and methods for treating occlusive intravascular lesions.

Catheters employing various types of ultrasound transmitting membershave been successfully used to ablate or otherwise disrupt obstructionsin blood vessels. Specifically, ablation of atherosclerotic plaque orthromboembolic obstructions from peripheral blood vessels such as thefemoral arteries has been particularly successful. Various ultrasoniccatheter devices have been developed for use in ablating or otherwiseremoving obstructive material from blood vessels. For example, U.S. Pat.Nos. 5,267,954 and 5,380,274, issued to an inventor of the presentinvention and hereby incorporated by reference, describe ultrasoundcatheter devices for removing occlusions. Other examples of ultrasonicablation devices for removing obstructions from blood vessels includethose described in U.S. Pat. No. 3,433,226 (Boyd), U.S. Pat. No.3,823,717 (Pohlman, et al.), U.S. Pat. No. 4,808,153 (Parisi), U.S. Pat.No. 4,936,281 (Stasz), U.S. Pat. No. 3,565,062 (Kuris), U.S. Pat. No.4,924,863 (Sterzer), U.S. Pat. No. 4,870,953 (Don Michael, et al), andU.S. Pat. No. 4,920,954 (Alliger, et al.), as well as other patentpublications W087-05739 (Cooper), W089-06515 (Bernstein, et al.),W090-0130 (Sonic Needle Corp.), EP316789 (Don Michael, et al.),DE3,821,836 (Schubert) and DE2438648 (Pohlman). While many ultrasoundcatheters have been developed, however, improvements are still beingpursued.

Typically, an ultrasonic catheter system for ablating occlusive materialincludes three basic components: an ultrasound generator, an ultrasoundtransducer, and an ultrasound catheter. The generator converts linepower into a high frequency current that is delivered to the transducer.The transducer contains piezoelectric crystals which, when excited bythe high frequency current, expand and contract at high frequency. Thesesmall, high-frequency expansions (relative to an axis of the transducerand the catheter) are amplified by the transducer horn into vibrationalenergy. The vibrations are then transmitted from the transducer throughthe ultrasound catheter via an ultrasound transmission member (or wire)running longitudinally through the catheter. The transmission membertransmits the vibrational energy to the distal end of the catheter wherethe energy is used to ablate or otherwise disrupt a vascularobstruction.

To effectively reach various sites for treatment of intravascularocclusions, ultrasound catheters of the type described above typicallyhave lengths of about 150 cm or longer. To permit the advancement ofsuch ultrasound catheters through small and/or tortuous blood vesselssuch as the aortic arch, coronary vessels, and peripheral vasculature ofthe lower extremities, the catheters (and their respective ultrasoundtransmission wires) must typically be sufficiently small and flexible.Also, due to attenuation of ultrasound energy along the long, thin,ultrasound transmission wire, a sufficient amount of vibrational energymust be applied at the proximal end of the wire to provide a desiredamount of energy at the distal end.

One continuing challenge in developing ultrasound catheters for treatingvascular occlusions is to provide adequate vibrational energy at thedistal end of a catheter device without overheating the ultrasoundtransmission wire. Generally, increasing the amount of power input tothe ultrasound transmission wire causes the temperature of the wire toincrease. Overheating may occur anywhere along the length of thetransmission wire, from its proximal connection with the ultrasoundtransducer to the distal tip of the wire. Overheating of the wire, alongwith the mechanical stresses placed on the wire from propagatingultrasound waves, can cause wire breakage, thus shortening the usefullife of the catheter device. Furthermore, it is generally desirable toablate an occlusion via the ultrasound vibrations and not by heating theocclusion, since heating causes a denaturalization process that reducesthe efficacy of the ultrasound ablation.

Some ultrasound catheters use irrigation fluid to attempt to control thetemperature of the ultrasound transmission wire, but such irrigationcooling techniques are not always effective. Other devices use swappedfrequencies to change frequency nodes and anti-nodes, thus moving a heatsource from point to point along the transmission wire. However, a givenultrasound transmission wire resonates at the fundamental frequency forwhich it is designed, and thus changing frequencies essentially requiresturning the ultrasound device on and off, which reduces the efficacy ofthe device. Some ultrasound catheter devices include one or moreabsorption members at the proximal end for absorbing unwanted vibrationsof the ultrasound transmission wire. Such absorbers, however, do notaddress the heat generation issue and, in fact, may cause increasedheating from frictional forces.

Therefore, a need exists for improved ultrasound catheter devices andmethods that provide ablation or disruption of vascular occlusions.Ideally, such ultrasound catheters would provide a desired level ofpower at a distal end of the device while also preventing overheating ofthe device's ultrasound transmission member. Ideally, such devices wouldaddress ultrasound transmission wire overheating at its proximalconnection with a catheter device as well as along the length of thewire. At least some of these objectives will be met by the presentinvention.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the invention, an ultrasound catheter for disruptingocclusions in blood vessels includes: an elongate flexible catheter bodyhaving a proximal end, a distal end and at least one lumen; anultrasound transmission member extending longitudinally through thelumen of the catheter body and having a proximal end and a distal end; adistal head coupled with the distal end of the ultrasound transmissionmember and disposed adjacent the distal end of the catheter body; asonic connector coupled with the proximal end of the ultrasoundtransmission member for coupling the ultrasound transmission member withan ultrasound transducer device; and a proximal housing coupled with theproximal end of the catheter body and housing the sonic connector and aproximal portion of the ultrasound transmission wire. The proximalhousing includes at least one heat dissipation feature for dissipatingheat from the proximal portion of the ultrasound transmission member.

In some embodiments, the heat dissipation feature comprises one or moreportions of the housing constructed of a heat conductive material. Forexample, the heat conductive material may include, but is not limitedto, metal, polymer, glass, rubber, combinations thereof, or the like.Additionally (or alternatively), the heat dissipation feature maycomprise multiple surface features on the housing to increase a surfacearea of the housing. Such surface features may include, for example,grooves, notches, waves, dips and/or the like. In some embodiments, anadditional or alternative heat dissipation feature comprises at leastone conductive material disposed within the housing, at least partiallyencircling the ultrasound transmission member, to conduct heat away fromthe ultrasound transmission member. In one embodiment, the conductivematerial may be disposed adjacent one or more vibration absorptionmembers surrounding the ultrasound transmission member. Optionally,multiple separate conductive members may be disposed between multiplevibration absorption members to at least partially encircle theultrasound transmission member. In another embodiment, the conductivematerial is arranged over one or more vibration absorption memberssurrounding the ultrasound transmission member.

In some embodiments, the heat dissipation feature comprises at least onefluid inlet for allowing passage of one or more heat dissipating fluidsinto an inner cavity of the housing. In some embodiments, the innercavity of the housing is in fluid communication with the lumen of thecatheter body, such that fluid introduced into the inner cavity passesthrough and out a distal end of the catheter body lumen. In someembodiments, the inlet is disposed along the housing such that the heatdissipating fluid(s) passing through the inlet contact at least onevibration absorption member disposed over the ultrasound transmissionmember. The inlet may also be disposed along the housing such that theheat dissipating fluid(s) passing through the inlet contact the sonicconnector and a portion of the ultrasound transmission member. Somedevices further include a refrigeration device coupled with the catheterfor refrigerating a fluid to be introduced through the fluid inlet.Optionally, the device may further include a guidewire tube extendingthrough at least a portion of the catheter body for allowing passage ofa guidewire. In one embodiment, a sidewall of the guidewire tubeincludes a plurality of apertures for allowing fluid introduced into thelumen of the catheter body to pass into and through the guidewire tube.

In some embodiments, at least a portion of the proximal housingcomprises a material adapted to change color when the temperature of thehousing changes. In one embodiment, for example, the material comprisesa thermochromic pigment. The thermochromic pigment, in one embodiment,may change from a first color to a second color when the temperature ofthe housing reaches approximately 45° Celsius and changes from thesecond color to the first color when the temperature of the housingdrops below approximately 45° Celsius.

In another aspect of the present invention, an ultrasound catheter fordisrupting occlusions in blood vessels includes: an elongate flexiblecatheter body having a proximal end, a distal end and at least onelumen; an ultrasound transmission member extending longitudinallythrough the lumen of the catheter body and having a proximal end and adistal end; a distal head coupled with the distal end of the ultrasoundtransmission member and disposed adjacent the distal end of the catheterbody; a sonic connector coupled with the proximal end of the ultrasoundtransmission member for coupling the ultrasound transmission member withan ultrasound transducer device; a proximal housing coupled with theproximal end of the catheter body and housing the sonic connector and aproximal portion of the ultrasound transmission wire; and heatdissipation means for dissipating heat from the ultrasound transmissionmember. According to various embodiments, heat dissipation means mayinclude any suitable members, devices, attachments or the likes, such asbut not limited to those described above. Any features described abovemay be applied to this ultrasound catheter.

In another aspect of the present invention, an ultrasound cathetersystem for disrupting occlusions in blood vessels includes an ultrasoundcatheter device, an ultrasound generator removably coupled with theultrasound catheter device, and a fluid cooling device removably coupledwith the ultrasound catheter device for cooling one or more heatdissipating fluids to be passed through the catheter device. Theultrasound catheter device itself includes: an elongate flexiblecatheter body having a proximal end, a distal end and at least onelumen; an ultrasound transmission member extending longitudinallythrough the lumen of the catheter body and having a proximal end and adistal end; a distal head coupled with the distal end of the ultrasoundtransmission member and disposed adjacent the distal end of the catheterbody; a sonic connector coupled with the proximal end of the ultrasoundtransmission member for coupling the ultrasound transmission member withan ultrasound transducer device; and a proximal housing coupled with theproximal end of the catheter body and housing the sonic connector and aproximal portion of the ultrasound transmission wire. The housingincludes at least one fluid inlet for allowing passage of one or moreheat dissipating fluids into an inner cavity of the housing. Again, theultrasound catheter may include any of the features described above.

In another aspect of the present invention, a method for disrupting anocclusion in a blood vessel involves positioning an ultrasound catheterin the blood vessel such that a distal end of the catheter is adjacentthe occlusion; transmitting ultrasound energy to an ultrasoundtransmission member of the ultrasound catheter to disrupt the occlusioninto multiple occlusion fragments, and passing a cooled irrigation fluidthrough the ultrasound catheter to dissipate heat away from theultrasound transmission member. In some embodiments, for example, thecooled fluid has a temperature between about 1° C. and about 22° C. Anysuitable cooled fluid may be used, such as but not limited to saline,thrombolytic agents, antiplatelet drugs, lysing agents, anticoagulantsand/or the like. In some embodiments, the method further involvescooling the irrigation fluid to a desired temperature, using arefrigeration device coupled with the ultrasound catheter. In oneembodiment, cooled fluid is passed continuously through the ultrasoundcatheter during an occlusion disruption procedure. Alternatively, thecooled fluid may be passed through the ultrasound catheter while thecatheter is activated, with fluid passage being automatically stoppedwhen the ultrasound catheter is deactivated.

In another aspect of the present invention, a method for disrupting anocclusion in a blood vessel involves positioning an ultrasound catheterin the blood vessel such that a distal end of the catheter is adjacentthe occlusion, transmitting ultrasound energy to an ultrasoundtransmission member of the ultrasound catheter to disrupt the occlusioninto multiple occlusion fragments, and passing an oxygen supersaturatedirrigation fluid through the ultrasound catheter to dissipate heat awayfrom the ultrasound transmission member. In some embodiments, forexample, the oxygen supersaturated irrigation fluid comprises oxygensupersaturated saline solution. In other embodiments, the oxygensupersaturated irrigation fluid comprises saline solution combined witha radiopaque contrast material. The oxygen supersaturead fluid may bekept at any suitable temperature. In some embodiments, the fluid is keptat room temperature, while in other embodiments it is kept at betweenabout 1° C. and about 22° C.

In another aspect of the present invention, a method for disrupting anocclusion in a blood vessel involves positioning an ultrasound catheterin the blood vessel such that a distal end of the catheter is adjacentthe occlusion, transmitting ultrasound energy to an ultrasoundtransmission member of the ultrasound catheter to disrupt the occlusioninto multiple occlusion fragments, and passing a lubricious irrigationfluid through the ultrasound catheter to dissipate heat away from theultrasound transmission member and reduce friction between theultrasound transmission member and an ultrasound catheter body. Forexample, in some embodiments, the lubricious irrigation fluid comprisesan emulsion. In one embodiment, the emulsion comprises olive oil, eggyolk, phospholipids, glycerin, sodium deoxycholate, L-histidine,disodium CDTA, sodium hydroxide and water. In some embodiments, theemulsion has a pH of between about 8.0 and about 9.0. The lubriciousfluid may be kept at any suitable temperature. In some embodiments, thefluid is kept at room temperature, while in other embodiments it is keptat between about 1° C. and about 22° C.

These and other aspects and embodiments of the present invention aredescribed in further detail below, in reference to the attached drawingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ultrasound catheter system accordingto an embodiment of the present invention;

FIG. 2 is a side view of an ultrasound catheter device according to anembodiment of the present invention;

FIG. 3 is cross-sectional side view of a proximal portion of anultrasound catheter device having heat dissipation means according to anembodiment of the present invention;

FIG. 4 is cross-sectional side view of a proximal portion of anultrasound catheter device having heat dissipation means according toanother embodiment of the present invention;

FIG. 5 is cross-sectional side view of a proximal portion of anultrasound catheter device having heat dissipation means according toanother embodiment of the present invention;

FIG. 6 is cross-sectional side view of a proximal portion of anultrasound catheter device, with a proximal housing of the device havinga fluid inlet aperture according to an embodiment of the presentinvention;

FIG. 7 is cross-sectional side view of a proximal portion of anultrasound catheter device, with a proximal housing of the device havinga fluid inlet aperture according to another embodiment of the presentinvention; and

FIG. 8 is a cross-sectional side view of a distal portion of anultrasound catheter device having a perforated guidewire tube forallowing passage of fluid therethrough according to another embodimentof the present invention

DETAILED DESCRIPTION OF THE INVENTION

Ultrasound catheter devices and methods of the present invention providefor disruption of occlusions in blood vessels. Catheter devicesgenerally include a catheter body, an ultrasound energy transmissionmember disposed within the catheter body and a distal head coupled withthe energy transmission member and disposed at or near the distal end ofthe catheter body. The ultrasound transmission member transmitsultrasound energy from an ultrasound transducer to the distal head,causing the head to vibrate and, thus, disrupt vascular occlusions. Anumber of improved features of such ultrasound catheter devices aredescribed more fully below.

Referring now to FIG. 1, one embodiment of an ultrasound catheter system20 suitably includes an ultrasound catheter device 10 and an ultrasoundgenerator 16. Catheter device 10 suitably includes a distal head 26 fordisrupting occlusions, a catheter body 27, and a proximal end connector12 for coupling catheter device 10 with an ultrasound transducer 14.Ultrasound transducer 14 is coupled with ultrasound generator 16 via aconnector 28, and generator is coupled with a foot-actuated on/offswitch 18 via another connector 29. Generator 16 provides ultrasonicenergy to transducer 14 and, thus, to ultrasound catheter 10. Catheterdevice 10 further includes an ultrasound transmission member (or“wire”—not shown) that extends through the catheter body 27 andtransmits energy from the transducer 14 to the distal head 26. Someembodiments of device 10 include a rapid exchange guidewire 13 andguidewire port, while other embodiments include a proximal guidewireport for over the wire guidewire delivery. In some embodiments,transducer 14 further includes a securing device 15 for enhancingcoupling of catheter 10 to transducer 14. The various components ofsystem 20 may be coupled via any suitable means. Connectors 28, 29 maycomprise an electric cord or cable or any other suitable connectingdevices for coupling on/off switch 18, generator 16 and transducer 14.In an alternative embodiment, on/off switch 18 is located on generator16.

In addition to proximal connector 12, ultrasound catheter device 10 mayinclude one or more other various components, such as a Y-connector 11including a fluid inlet port 17 (or aperture) for passage of irrigationfluid. Inlet port 17 may be removably coupled with an irrigation tube24, which in one embodiment may be coupled with a fluid refrigeration(or “fluid cooling”) device 30. Refrigeration device 30 may, in turn, becoupled with a fluid container 32 via a connector tube 34. Thisirrigation apparatus may be used for introducing one or more fluids intocatheter device 10. Fluid may be used to cool any part of the device,such as the ultrasound transmission member, thus helping reduce wear andtear of device 10. In some embodiments, fluid inlet port 17 is locatedfarther proximally on proximal connector 12, to allow fluid to beapplied within connector 12. In some embodiments, refrigerated fluid isused, while in other embodiments irrigation fluid may be kept at roomtemperature. In various embodiments, oxygen supersaturated fluid,lubricious fluid, or any other suitable fluid or combination of fluidsmay be used, and again, such fluids may be refrigerated or kept roomtemperature. In an alternative embodiment to that shown in FIG. 1,refrigeration device 30 and fluid container 32 are combined in onedevice.

Generally, catheter device 10 may include any suitable number ofside-arms or ports for passage of a guidewire, application of suction,infusing and/or withdrawing irrigation fluid, dye and/or the like, orany other suitable ports or connections. Also, ultrasound catheters 10of the present invention may be used with any suitable proximal devices,such as any suitable ultrasound transducer 14, ultrasound generator 16,coupling device(s) and/or the like. Therefore, the exemplary embodimentshown in FIG. 1 and any following descriptions of proximal apparatus orsystems for use with ultrasound catheters 10 should not be interpretedto limit the scope of the present invention as defined in the appendedclaims.

Referring now to FIG. 2, an enlarged view of catheter device 10 isshown. Proximal connector 12, Y-connector 11, inlet port 17, catheterbody 27, distal head 26 and guidewire 13 are all shown. Catheter body 27is generally a flexible, tubular, elongate member, having any suitablediameter and length for reaching a vascular occlusion for treatment. Inone embodiment, for example, catheter body 27 preferably has an outerdiameter of between about 0.5 mm and about 5.0 mm. In other embodiments,as in catheters intended for use in relatively small vessels, catheterbody 27 may have an outer diameter of between about 0.25 mm and about2.5 mm. Catheter body 27 may also have any suitable length. As discussedbriefly above, for example, some ultrasound catheters have a length inthe range of about 150 cm. However, any other suitable length may beused without departing from the scope of the present invention. Examplesof catheter bodies similar to those which may be used in the presentinvention are described in U.S. Pat. Nos. 5,267,954 and 5,989,208, whichwere previously incorporated herein by reference.

Features of the present invention may be applied to any of a number ofultrasound catheter devices. For more detailed description of exemplaryultrasound catheter devices, reference may be made to U.S. patentapplication Ser. Nos. 10/229,371, 10/345,078, 10/375,903, 10/410,617 and10/722,209, which were all previously incorporated by reference. Invarious alternative embodiments, aspects of the present invention may beapplied to any other suitable catheter devices.

Referring now to FIG. 3, a proximal portion of one embodiment of anultrasound catheter device 110 is shown in cross-section. An ultrasoundtransmission wire 140 extends from a sonic connector 152 distally to adistal end (not shown) of catheter device 110. A catheter body 127 ofdevice 110 is shown only in part, whereas catheter body 127 typicallyextends distally to (or near) the distal end of device 110. Catheterdevice 110 also includes a proximal housing 112 (or “proximalconnector”), having an inner bore 144 (or “inner cavity”) in which sonicconnector 152, a portion of ultrasound transmission member 140 and oneor more vibration absorption members 150 reside. Housing 112 is coupledwith a Y-connector 111, which includes a fluid inlet port 117 (oraperture), and Y-connector 111 is coupled with catheter body 127.

In various embodiments, housing 112 may suitably include one or moresurface features 142 for increasing the overall surface area of theouter surface of housing 112. Increased surface area enhances theability of housing 112 to dissipate heat generated by ultrasoundtransmission member 140 out of catheter device 110. Surface features 142may have any suitable size or shape, such as ridges, jags, undulations,grooves or the like, and any suitable number of surface features 142 maybe used. Additionally, housing 112 may be made of one or more heatdissipating materials, such as aluminum, stainless steel, any otherconductive metal(s), or any suitable non-metallic conductivematerial(s).

In most embodiments, ultrasound transmission member 140, wire, or waveguide extends longitudinally through a lumen of catheter body 127 totransmit ultrasonic energy from an ultrasound transducer (not shown),connected to the proximal end of proximal housing 112, to the distal endof catheter device 110. Ultrasound transmission member 140 may be formedof any material capable of effectively transmitting ultrasonic energyfrom the ultrasound transducer to the distal end of catheter body 127,including but not limited to metals such as pure titanium or aluminum,or titanium or aluminum alloys. Again, additional details of ultrasoundtransmission members 140 may be found in the patent applicationsincorporated by reference above. Similarly, reference may be made to theincorporated patent applications for descriptions of housing 112, sonicconnector 152, vibration absorption members 150, Y-connector 111 and thelike. For example, housing 112 and other features are described indetail in Ser. No. 10/722,209, filed Nov. 24, 2003, entitled “SteerableUltrasound Catheter” (Attorney Docket No. 021577-000900US), which waspreviously incorporated by reference.

Ultrasound transmission member 140 typically passes from sonic connector152, through bore 144 and Y-connector 111, and then through catheterbody 127. Fluid inlet port 117 is in fluid communication with a lumen inY-connector, which is in fluid communication with a lumen extendingthrough catheter body 127. Thus, fluid introduced into fluid inlet port117 is typically free to flow into and through catheter body 127 tocontact ultrasound transmission member 140. Fluid may flow out ofcatheter body 127 through apertures in the distal head (not shown) orthrough any other suitable apertures or openings, such as apertureslocated in catheter body 127 itself. Any suitable fluid may be passedthrough fluid inlet port 117 and catheter body 127, such as refrigeratedfluid, lubricious fluid, super-saturated saline or contrast/salinemixture, or the like. Cooling and/or lubricating ultrasound transmissionmember 140 may reduce friction and/or wear and tear of ultrasoundtransmission member 140, thus prolonging the useful life of ultrasoundcatheter device 110 and enhancing its performance.

Additionally, the temperature and flow rate of a coolant liquid may bespecifically controlled to maintain the temperature of ultrasoundtransmission member 140 at a desired temperature within its optimalworking range. In particular, in embodiments of the invention whereultrasound transmission member 140 is formed of a metal alloy whichexhibits optimal physical properties (e.g. super elasticity) within aspecific range of temperatures, the temperature and flow rate of coolantliquid infused through fluid inlet port 117 may be specificallycontrolled to maintain the temperature of ultrasound transmission member140 within a range of temperatures at which it demonstrates its mostdesirable physical properties. For example, in embodiments of theinvention where ultrasound transmission member 140 is formed of a shapememory alloy which exhibits super-elasticity when in its martensitestate, but which loses super-elasticity as it transitions to anaustenite state, it will be desirable to adjust the temperature and flowrate of the coolant liquid infused through fluid inlet port 117 tomaintain the shape memory alloy of ultrasound transmission member 140within a temperature range at which the alloy will remain in itsmartensite state and will not transition to an austenite state. Thetemperature at which such shape memory alloys transition from amartensite state to an austenite state is known as the “martensitetransition temperature” of the material. Thus, in these embodiments, thefluid infused through port 117 will be at such temperature, and will beinfused at such rate, as to maintain the shape memory alloy ofultrasound transmission member 140 below its martensite transitiontemperature.

As mentioned above, in one embodiment, a super-saturated fluid may beused. Use of such fluids may enhance cavitation of an occlusion, helpprevent unwanted tissue damage and/or the like. Such fluids aredescribed, for example, in U.S. Pat. Nos. 6,676,900, 6,622,542,6,613,280, 6,607,698, 6,605,217, 6,602,468, 6,602,467, 6,596,235,6,582,387, 6,576,807, 6,558,502, 6,555,059, 6,533,766, 6,454,997,6,387,324, 6,346,192, 6,315,754, 6,248,087, 6,235,007, 6,180,059,6,142,971, 6,123,698, 6,030,357, 5,976,119, 5,957,889, 5,893,838 and5,797,876, which are hereby incorporated by reference. In anotherembodiment, a mixture of contrast dye and saline may be used to achievethe same or similar results.

With reference now to FIG. 4, one embodiment of an ultrasound catheterdevice 210 includes the features described immediately above and alsoincludes a heat absorbing member 160 disposed within housing 112. Heatabsorbing member 160 may have any suitable shape and size and may, invarious embodiments, be disposed in any of a number of differentlocations within housing 112. Typically, heat absorbing member 160 ismade of a heat absorbing material, such as but not limited to ametalized elastomer, such as a rubber material combined with a metallicpowder such as aluminum powder. Of course, any other suitable heat sinkor heat absorption material may be used, in alternative embodiments. Inthe embodiment shown, heat absorbing member 160 is generally cylindricalin shape and is disposed around vibration absorption members 150, sothat it absorbs heat from ultrasound transmission member 140 andvibration absorbers 150.

Referring to FIG. 5, in an alternative embodiment an ultrasound catheterdevice 310 may include multiple heat absorption members 170, such ascylindrical members disposed around ultrasound transmission member 140and in between multiple vibration absorption members 150. As is evidentfrom FIGS. 4 and 5, any of a number of configurations of heat absorptionmembers 160, 170 may be disposed within housing 112.

FIG. 6 demonstrates another embodiment of an ultrasound catheter device410, which may include any of the features described above. In thisembodiment, a fluid inlet port 217 is located farther proximally onhousing 112 than in the earlier-described embodiments. Fluid inlet port217 is in fluid communication with inner cavity 144 of housing 112, sothat fluid (solid-tipped arrows) introduced into fluid inlet port 217enters inner cavity 144 and contacts vibration absorption members 150before entering the lumen of catheter body 127 via one or more proximalapertures 220. Fluid passing along and contacting vibration absorptionmembers 150 will help dissipate heat from the members 150. As mentionedabove, such fluids may be refrigerated/cooled, lubricious, oxygensupersaturated or the like. Lubricious and oxygen supersaturated fluids,in various embodiments, may be either cooled/refrigerated or at roomtemperature.

Referring to FIG. 7, another embodiment of an ultrasound catheter device510 includes all the features just described, but fluid inlet port 317is located farther proximally on housing 112. In this embodiment, fluid(solid-tipped arrows) entering fluid inlet port 317 contacts a proximalportion of ultrasound transmission member 140, proceeds distally tocontact vibration absorption members 150, and then proceeds throughapertures 220 into the lumen of catheter body 127. Thus, the fluidprovides extra heat dissipation to the proximal portion of ultrasoundtransmission member 140 with which it comes in contact.

As mentioned above, in some embodiments irrigation/cooling fluid passesthrough a lumen of catheter body 127 and out one or more apertures indistal head 26 or elsewhere on the catheter device. In an alternativeembodiment, and with reference now to FIG. 8, an ultrasound catheterdevice 610 may include a guidewire tube 424 that forms a guidewire lumen426 and that includes one or more guidewire tube apertures 430 forallowing passage of fluid. Generally, a guidewire 420 may be passedthrough guidewire lumen 426 and out a distal aperture 422 of guidewiretube 424, located in distal head 26. Fluid (solid-tipped arrows) that ispassed through a catheter body lumen 428 may flow into apertures 430 andout distal aperture 422. The fluid would thus contact ultrasoundtransmission member 140 during a portion of its journey through catheterbody lumen 428, thus dissipating heat and/or lubricating, and would thenpass out of catheter device 610 via guidewire tube 424. Thisconfiguration may be advantageous in that irrigation fluid may providean additional lubrication inside guidewire lumen 426 to improveguidewire movement.

In one embodiment, housing 112 may include a material that changes colorwhen its temperature increases or decreases, thus providing anindication of the temperature of the proximal portion of the catheterdevice. In one embodiment, for example, a thermochromic material, suchas Colorcomp® Thermochromics (provided by LNP Engineering Plastics,Inc.) may be used. Other color-change materials may be used inalternative embodiments. In various embodiments, the color of suchmaterial may change at any suitable temperatures. In one embodiment, forexample, the thermochromic pigment changes from a first color to asecond color when the temperature of housing 112 reaches approximately45° Celsius and changes from the second color to the first color whenthe temperature of housing 112 drops below approximately 45° Celsius.

Although the invention has been described above with specific referenceto various embodiments and examples, it should be understood thatvarious additions, modifications, deletions and alterations may be madeto such embodiments without departing from the spirit or scope of theinvention. Accordingly, it is intended that all reasonably foreseeableadditions, deletions, alterations and modifications be included withinthe scope of the invention as defined in the following claims.

1.-40. (canceled)
 41. An ultrasound catheter system for disruptingocclusions in blood vessels, the system comprising: an ultrasoundcatheter device, comprising: an elongate flexible catheter body having aproximal end, a distal end and at least one lumen; an ultrasoundtransmission member extending longitudinally through the lumen of thecatheter body and having a proximal end and a distal end; a distal headcoupled with the distal end of the ultrasound transmission member anddisposed adjacent the distal end of the catheter body; a sonic connectorcoupled with the proximal end of the ultrasound transmission member forcoupling the ultrasound transmission member with an ultrasoundtransducer device; and a proximal housing coupled with the proximal endof the catheter body and housing the sonic connector and a proximalportion of the ultrasound transmission wire, wherein the housingincludes at least one fluid inlet for allowing passage of one or moreheat dissipating fluids into an inner cavity of the housing; anultrasound generator removably coupled with the ultrasound catheterdevice; and a fluid cooling device removably coupled with the ultrasoundcatheter device for cooling the heat dissipating fluid(s).
 42. A systemas in claim 41, wherein one or more portions of the housing areconstructed of a heat conductive material.
 43. A system as in claim 42,wherein the heat conductive material is selected from the groupconsisting of metal, polymer, glass, rubber and combinations thereof.44. A system as in claim 42, wherein the housing further comprisesmultiple surface features to increase a surface area of the housing. 45.A system as in claim 44, wherein the surface features are selected fromthe group consisting of grooves, notches, waves and dips.
 46. A systemas in claim 41, further comprising at least one conductive materialdisposed within the housing, at least partially encircling theultrasound transmission member, to conduct heat away from the ultrasoundtransmission member.
 47. A system as in claim 46, wherein the conductivematerial is disposed adjacent one or more vibration absorption memberssurrounding the ultrasound transmission member.
 48. A system as in claim47, wherein the at least one conductive material comprises multipleseparate conductive members disposed between multiple vibrationabsorption members and at least partially encircling the ultrasoundtransmission member.
 49. A system as in claim 46, wherein the conductivematerial is arranged over one or more vibration absorption memberssurrounding the ultrasound transmission member.
 50. A system as in claim41, wherein the inner cavity of the housing is in fluid communicationwith the lumen of the catheter body, such that fluid introduced into theinner cavity passes through and out a distal end of the catheter bodylumen.
 51. A system as in claim 41, wherein the inlet is disposed alongthe housing such that the heat dissipating fluid(s) passing through theinlet contact a proximal portion of the ultrasound transmission member.52. A system as in claim 41, wherein the inlet is disposed along thehousing such that the heat dissipating fluid(s) passing through theinlet contact at least one vibration absorption member disposed over theultrasound transmission member.
 53. A system as in claim 41, wherein theinlet is disposed along the housing such that the heat dissipatingfluid(s) passing through the inlet contact the sonic connector and aportion of the ultrasound transmission member.
 54. (canceled) 55.(canceled)
 56. A system as in claim 41, wherein at least a portion ofthe proximal housing comprises a material adapted to change color whenthe temperature of the housing changes.
 57. A system as in claim 56,wherein the material comprises a thermochromic pigment.
 58. A system asin claim 57, wherein the thermochromic pigment changes from a firstcolor to a second color when the temperature of the housing reachesapproximately 45° Celsius and changes from the second color to the firstcolor when the temperature of the housing drops below approximately 45°Celsius.
 59. A method for disrupting an occlusion in a blood vessel, themethod comprising: positioning an ultrasound catheter in the bloodvessel such that a distal end of the catheter is adjacent the occlusion;transmitting ultrasound energy to an ultrasound transmission member ofthe ultrasound catheter to disrupt the occlusion into multiple occlusionfragments; and passing a cooled irrigation fluid through the ultrasoundcatheter to dissipate heat away from the ultrasound transmission member.60. A method as in claim 59, wherein the cooled fluid has a temperaturebetween 1° C. and 22° C.
 61. A method as in claim 59, wherein the cooledfluid is selected from the group consisting of saline, thrombolyticagents, antiplatelet drugs, lysing agents and anticoagulants.
 62. Amethod as in claim 59, further comprising cooling the irrigation fluidto a desired temperature, using a refrigeration device coupled with theultrasound catheter.
 63. A method as in claim 59, wherein the cooledfluid is passed continuously through the ultrasound catheter during anocclusion disruption procedure.
 64. A method as in claim 59, wherein thecooled fluid is passed through the ultrasound catheter while thecatheter is activated and fluid passage is automatically stopped whenthe ultrasound catheter is deactivated.
 65. A method for disrupting anocclusion in a blood vessel, the method comprising: positioning anultrasound catheter in the blood vessel such that a distal end of thecatheter is adjacent the occlusion; transmitting ultrasound energy to anultrasound transmission member of the ultrasound catheter to disrupt theocclusion into multiple occlusion fragments; and passing an oxygensupersaturated irrigation fluid through the ultrasound catheter todissipate heat away from the ultrasound transmission member.
 66. Amethod as in claim 65, wherein the oxygen supersaturated irrigationfluid comprises oxygen supersaturated saline solution.
 67. A method asin claim 65, wherein the oxygen supersaturated irrigation fluidcomprises saline solution combined with a radiopaque contrast material.68. A method as in claim 65, wherein the oxygen supersaturatedirrigation fluid has a temperature approximately the same as a roomtemperature.
 69. A method as in claim 65, wherein the oxygensupersaturated irrigation fluid has a temperature between 1° C. and 22°C.
 70. A method for disrupting an occlusion in a blood vessel, themethod comprising: positioning an ultrasound catheter in the bloodvessel such that a distal end of the catheter is adjacent the occlusion;transmitting ultrasound energy to an ultrasound transmission member ofthe ultrasound catheter to disrupt the occlusion into multiple occlusionfragments; and passing a lubricious irrigation fluid through theultrasound catheter to dissipate heat away from the ultrasoundtransmission member and reduce friction between the ultrasoundtransmission member and an ultrasound catheter body.
 71. A method as inclaim 70, wherein the lubricious irrigation fluid comprises an emulsion.72. A method as in claim 71, wherein the emulsion comprises olive oil,egg yolk, phospholipids, glycerin, sodium deoxycholate, L-histidine,disodium CDTA, sodium hydroxide and water.
 73. A method as in claim 71,wherein the emulsion has a pH of between 8.0 and 9.0.
 74. A method as inclaim 70, wherein the lubricious irrigation fluid has a temperatureapproximately the same as a room temperature.
 75. A method as in claim70, wherein the lubricious irrigation fluid has a temperature between 1°C. and 22° C.
 76. A system as in claim 52, wherein the inlet is disposedalong the housing such that the heat dissipating fluid(s) passingthrough the inlet contact the sonic connector and a portion of theultrasound transmission member.